Allergy and Anaphylaxis Flashcards
Hypersensitivity reactions can be caused by reactions against what 3 things
Microbes
Self
Environmental antigens
Immediate hypersensitivity definition
Begins rapidly (within minutes) of antigen challenge Has major pathological consequences
Late phase reaction is characterized by the accumulation of which cells?
Neutrophils
Eosinophils
Macrophages
Why is it important to properly classify the hypersensitivity?
So we can determine what type of testing should be performed
Type 2 hypersensitivity
Antibody mediated
IgM, IgG antibodies against cell surface or extracellular matrix antigens
Autoimmune diseases
Type 3 hypersensitivity
Immune complex mediated
Immune complexes of circulating antigens and IgM or IgG bound to self or foreign antigens
Where the complexes are deposited determines the pathology
Systemic diseases (multiple tissues and organs)
Type 4 hypersensitivity
T cell mediated
Mechanism depends on which T cell subtype is involved
CD4: trigger inflammation
CD8: directly kill target cells
Sign vs symptom
Sign: Indication of a medical condition that can be objectively observed
Symptom: Manifestation of the condition that is apparent to the patient
The hallmark of allergic diseases is…
The production of IgE
Dependent on the activation of CD4 cells that produce IL-4
What is released from mast cells
- Immediate
- Over minutes
- Over hours
- Granule contents (histamine, proteases, etc)
- Lipid mediators (prostaglandins, leukotrienes)
- Cytokines (IL4, 13)
6 main allergy symptoms from mast cell release
Vasodilation Vascular lead Bronchoconstriction Intestinal hypermotility Inflammation Tissue damage
2 main functions of CD4+ T cells
Recruit and activate phagocytes
Help B cells produce antibodies
3 types of CD4 T cells
Th1
Th2
Th17
5 signs of urticaria
Raised Erythematous Central clearing Irregular border Often migratory
Angioedema
Swelling of the soft tissues
Localized to subcutaneous or submucosal tissues (face, lips, mouth, eyelids, upper airway)
Never involved gravity-dependent areas (legs)
Onset within minutes to 2-3 hours from IgE reaction
3 ways IgG and IgM cause tissue injury
Activating the complement system
Recruiting inflammatory cells
Interfering with normal cellular functions
3 criteria to diagnose anaphylaxis
- Acute onset of illness with skin/mucosal involvement and at least one of resp symptoms or reduced BP/signs of end organ dysfunction
- If there is a likely allergen for that patient, 2 of the following: skin/mucosal involvement, resp compromise, reduced BP, GI symptoms
- Reduced BP after exposure to known allergen for that patient
3 second line treatments for anaphylaxis
H1 antihistamine (for itching, flushing, urticaria, angioedema, nose and eye symptoms)
Glucocorticoids (ex: prednisone - turns off activated genes for pro-inflammatory proteins)
Inhaled beta2 adrenergic agonists (helpful for lower resp tract symptoms)
Standard and Junior Epipen doses
S: 0.3 mg (over 30kg)
J: 0.15 mg (15-30 kg)
